Process of making disazo dyestuffs



Patented Sept. 11, 1951 PROCESS OF MAKING DISAZO DYESTUFFS Fritz Straub, Kaiseraugst, and Jakob Brassel and Peter Pieth, Basel, Switzerland, assignors to Ciba Limited, Basel, Switzerland, a Swiss firm No Drawing. Application December 29, 1947, Serial No. 794,458

4 Claims. 1 This application is a continuation-in-part of our copending applications, Serial No. 431,172,

filed February 16, 1942 (now abandoned), and

Serial No. 498,882, filed August 16, 1943 (now abandoned), the latter being a continuation-inpart of the former.

U. S. Patent No. 1,210,751 describes a process for the manufacture of a dyestuff, wherein tetrazotized 3:3'dihydroxy-4:4'diaminodiphenyl is brought together with two mols of 2-amino-5- hydroxynaphthalene-7-sulfonic acid in a medium which has been rendered alkaline with sodium carbonate. That patent also states that the reaction proceeds very slowly and that a dyestuff is formed which dyes cotton in violet tints. In carrying out this process, we have found that the resultant product does not at all meet modern requirements. The uncoppered as well as the coppered dyeings obtained therewith are quite insufficiently fast to washing. Further examination of the process of the aforementioned patent has shown that, contrary to what the inventors apparently believed, the result is not the expected disazo dyestufi and that for about 90 percent. coupling takes place on but one side so that a monoazo dyestuff is formed plus only about 10 per cent. of the disazo dyestufi.

We have now discovered that very valuable disazo dyestuffs which are substantially free from monoazo dyestulfs and which, when after-coppered, produce blue, wash-fast dyeings on cotton, can be prepared by coupling tetrazotized 3:3- dihydroxy-4:4-diamino-diphenyl with 2 mols of an amino-5-hydroxynaphthalene-7-sulfonic acid capable of coupling in the fi-positlon, the amino group of which is in a p-position, but not, of course, in the 6-position, and bringing about coupling in a medium rendered alkaline with a hydroxide of the alkaline earth metal series.

3:3 dihydroxy 4:4 diaminodiphenyl is a known compound and may be obtained, for instance, by saponifying 3:3-dimethoxy-4:4'-diaminodiphenyl by means of aluminum chloride and may be purified, if necessary, accordin to known methods. It may be tetrazotized in known manner and the tetrazo compound may be used immediately after tetrazotizing or may be separated as described in the examples below. Coupling componentswhich may be used under our process are amino-5-hydroxynaphthalene-7- sulfonic acids which are capable of coupling in the 6-position and which carry theamino group in a fi-position other than the 6-position, that is to say, in the 2- or 3-position. Such coupling components are, therefore, either 2-amino-5-hy- 2 droxynaphthalene-7-sulfonic acid or 3-amino-5- hydroxynaphthalene-7-sulfonic acid. The lat ter compound is usually called 2-amino-8-hydroxynaphthalene-6-sulfonic acid.

Alkaline earth metal hydroxides are here intended to meanin conformity with the usual definition in text booksthe hydroxides of calcium, strontium or barium, to the exclusion of magnesium hydroxide. Of these, calcium hydroxide is the most suitable for our process.

Coupling is advantageousy carried out at a high concentration. The amino-hydroxynaphthalene-sulfonic acid serving as coupling component may be used as a free acid or as an alkali salt, for example, the sodium salt. The coupling reaction requires quite some time. Its course can be accelerated by gradually increasing the temperature and/or by the addition of suitable reaction promoters, such as, for example, a small quantity of pyridine. If desired, the dyestuif which, for the greater part, separates during the coupling in the form of a salt of an alkaline earth metal may be separated from the suspension by means of filtration before it is freed from the alkaline earth metal. Such freeing is usually necessary to make the product better suitable for dyeing. It is effected, for example, by treatment with an alkali carbonate, advantageously at a raised temperature, which causes the dyestufi to dissolve as an alkali salt. The solution is separated from the alkaline earth metal carbonate by means of filtration, .and the dyestuff is finally separated by the addition of sodium chloride and/or mineral acid, for example, hydrochloric acid.

The disazo-dyestuffs obtainable according to the present process correspond in their free acid state to the general formula wherein each of the napthalene radicals carries one NHz-group in a B-position. They are substantially free from admixed monoazo-dyestuff and produce blue after-coppered shades on cotton.

They are suitable for dyeing and printing the most diverse materials, especially cellulose fibers, such as linen, cotton, and other vegetable fibers as well as cellulose, rayons and staple fibers. Owing to their derivation from an ortho -hydroxydiazo compound, these dyestufis are-capable of forming metal compounds, for instance, with the pended in 2000 parts of water, the suspension is metals copper, cobalt, nickel, iron, chromium, heated to 60 C., 400 parts by weight of sodium vanadium, manganese. With these dyestuffs it carbonate of 20 per cent. strength are then added is advantageous to effect metallization during or, and the precipitated calcium carbonate is filstill better, after dyeing according to the known 5 tered off. To the filtrate there are first added after-treating, for instance after-coppering, 120 parts of sodium chloride and then the quanmethods. With special advantage use may be tity of percent. hydrochloric acid which is made of the dyeing methods described in U. S. necessary to obtain a reaction weakly alkaline Patents 2,148,659 and 2,185,905, according to to phenolphthalein. Finally, the precipitated which metallizing is preferably carried out with 10 dyestuff is filtered off and dried. It has the agents yielding metal which are stable towards same properties as the dyestuif obtained in acalkalis, for instance, complex tartrates of copper. cordance with the prescriptions of Example 1.

The following examples illustrate the invention, the parts being by weight unless otherwise Example 3 Stated: 21.6 parts of 3:3-dihydroxy-4:4-dian1inodi- Example 1 phenyl are tetrazotized as described in Example 21, parts of 313'-dihyd10 y-4;4-diaminodi- 1, the solution is neutralized with sodium carbophenyl, in th form of t dichlorhydrate, are nate solution and the precipitated tetrazo comstirred in 100 parts of water and 12 parts of conp d is filtered O f. centrated hydrochloric acid and are tetrazotized parts Of yd Xy- D thaleneby dditi of n aqueous 1 11 11 of 13,8 -t G-sulfonic acid are stirred into 250 parts of water of sodium nitrite at 5-8 C. When tetrazotizad 29-6 parts of Slaked lime are added. .The tion is complete, the suspension is cooled to 3 0., p sion is cooled to 5 C.. and the filtered neutralized by addition of 6.4 parts of sodium tetrazo compound is added. The coupling temcarbonate and filtered to obtain the precipitated p r is maintained for 2 hours at tetrazo compound then for 48 hours at lO-15 C. and, finally, at This tetrazo compound is introduced into a 0 5 C- unt l the reaction is p t The paste of 48.8 parts of 2-amino5-hydroxynaphcoupling mass is then diluted with 1000 parts of thalene-l-sulfonic acid and 29.6 parts of calwater at 50 C. a solution of 60 parts of sodium cium hydroxide in 200 parts of water cooled to carbonate in 300 parts of water is added and 5 C. Coupling is carried out for 2 hours at 5-8 the precipitated calcium carbonate is filtered off. C. at first, then the reaction is completed by stir- To the filtrate, 60 parts of sodium chloride and ring for several hours at 10-20 C. The coupling then, in drops, 110 parts of 10 per cent. hydromixture is then diluted with 2000 parts of water chloric acid are added. The new dyestuff is filat C., 60 parts of sodium carbonate are added tered on? and dried. and the precipitated calcium carbonate is fil- It possesses the formula H... aaQQnM at... SO H H H Hols tered on. 140 parts of 10 percent hydrochloric and is a bronzy black powder which dissolves in acid are added to the filtrate and the new dyewater with a blackish blue-violet, in 10 per cent. stuff is obtained by salting out. 45 soda solution with a blue, in 10 per cent. caustic When dry, it is a bronzy black powder of the soda with a red-violet and in concentrated sulformula furic acid with a green-blue color. When dyed H2N SO3H H038 -NH:

and dissolves in water to a blue-violet, in 10 peron cotton; and after-treated with copper salts,

cent soda solution to a reddish blue, in 10 percent in either a one or a two bath process,- it yields caustic soda to a red violet, and in concentrated blue shades of very good fastness properties. sulfuric acid to a green-blue solution. When dyed on cotton and after-treated with copper Example 4 salts in a one or two bath process, it yields-fast A dyebath is made up from 4000 parts of water, b ue shades- 2 parts of anhydrous sodium carbonate and 2 Emmple 2 parts of the dyestufi obtained according to Ex- 21.6 parts of 3:3'-.dihydroxy-4:4-diaminodiample 1. 100 parts of cotton are entered at phenyl are tetrazotized as described in Example 60 C. The bath is heated to the boil within 20 1, The preci itated tetrazo compound is filtered minutes. 30 parts of crystallized Sodium sulfate off and introduced into a paste of 58 parts of are added and dyeing is continued for 45 minthe mono-sodium salt of 2-amino-5-hydroxyutes at about 100 C. The bath is then cooled naphthalene-'l-sulfonic acid and 34 parts of to 75-80" C., 1.5 parts of complex copper sodium calcium hydroxide in 200 parts of water cooled tartrate, containing 0.23 part of copper and preto 2 C. Coupling is carried on for 4 hours at viously dissolved in water, are added and the dye- 2-10 C. and then for 20 hours at Ill-20 C. The ing is coppered for 40 minutes at 80-90 C. coupling mixture is then diluted with 400 parts Finally, the coppered dyeing is rinsed with cold of a sodium chloride solution of 70 C. and 7 water, if desired, soaped at 50 C. in a bath conper cent. strength and the calcium salt of the taining 5 grams of curd soap and 2 grams of dyestufi is filtered ofi. The filter cake is susanhydrous sodium carbonate per liter of water.

and dried. The cotton is dyed in a fast pure blue shade.

What we claim is:

1. Process for the manufacture of a disazo dyestufi which comprises coupling tetrazotized 3:3- dihydroxy-4:4'-diaminodiphenyl with two molecular proportions of an amino-S-hydroxynaphthalene-7-sulfonic acid capable of coupling in G-position and wherein the amino group is a primary amino group in a B-position, in a medium rendered alkaline with an alkaline earth metal hydroxide.

2. Process for the manufacture of a disazo dyestuff which comprises coupling tetrazotized 3:3-

dihydroxy-4:4'-diaminodiphenyl with two mo- 15 lecular proportions of an amino-S-hydroxynaphtha1ene-7-sulfonic acid capable of coupling in 6-position and wherein the amino group is a primary amino group in a ,B-posltion, in a medium rendered alkaline with calcium hydroxide.

3. Process for the manufacture of a disazo dyestufi which comprises coupling tetrazotized 3:3- dihydroxy-4:4'-diaminodiphenyl with two molecular proportions of 2-amino-5-hydroxynaphthalene-7-sulfonic acid in a medium rendered alkaline with calcium hydroxide.

4. Process for the manufacture of a disazo dyestuff which comprises coupling tetrazotized 3:3- dihydroxy-4:4-diaminodiphenyl with two molecular proportions of 2-amino-8-hydroxynaphthalene-fi-sulfonic acid in a medium rendered alkaline with calcium hydroxide.

FRITZ STRAUB. JAKOB BRASSEL. PETER PIETH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 521,096 Bernthsen et a1 1 June 5, 1894 964,918 Laska July 19, 1910 1,210,751 Anderwert et al. Jan. 2, 1917 1,921,361 Laska et al. Aug. 8, 1933 2,042,810 Straub et al. June 2, 1936 2,257,165 Fellmer Sept. 30, 1941 2,428,130 Straub et a1. Sept. 30, 1947 2,437,699 Lancius et al Mar. 16, 1948 FOREIGN PATENTS Number Country Date 102,881 Great Britain June 4, 1917 113,141 Great Britain Feb. 8. 1918 

4. PROCESS FOR THE MANUFACTURE OF A DISAZO DYESTUFF WHICH COMPRISES COUPLING TETRAZOTIZED 3:3''DIHYDROXY-4:4''-DIAMINODIPHENYL WITH TWO MOLECULAR PROPORTIONS OF AN AMINO-5-HYDROXYNAPHTHALENE-7-SULFONIC ACID CAPABLE OF COUPLING IN 6-POSITION AND WHEREIN THE AMINO GROUP IS A PRIMARY AMINO GROUP IN A B-POSITION, IN A MEDIUM RENDERED ALKALINE WITH AN ALKALINE EARTH METAL HYDROXIDE. 